HTC Vive Gives Autonomous Robots Direction

The HTC Vive is a virtual reality system designed to work with Steam VR. The system seeks to go beyond just a headset in order to make an entire room a virtual reality environment by using two base stations that track the headset and controller in space. The hardware is very exciting because of the potential to expand gaming and other VR experiences, but it’s already showing significant potential for hackers as well — in this case with robotics location and navigation.

Autonomous robots generally utilize one of two basic approaches for locating themselves: onboard sensors and mapping to see the world around it (like how you’d get your bearings while hiking), or sensors in the room which tell the robot where it is (similar to your GPS telling you where you are in the city). Each method has its strengths and weaknesses, of course. Onboard sensors are traditionally expensive if you need very accurate position data, and GPS location data is far too inaccurate to be of use on a smaller scale than city streets.

[Limor] immediately saw the potential in the HTC Vive to solve this problem, at least for indoor applications. Using the Vive Lighthouse base stations, he’s able to locate the system’s controller in 3D space to within 0.3mm. He’s then able to use this data on a Linux system and integrate it into ROS (Robot Operating System). [Limor] hasn’t yet built a robot to utilize this approach, but the significant cost savings ($800 for a complete Vive, but only the Lighthouses and controller are needed) is sure to make this a desirable option for a lot of robot builders. And, as we’ve seen, integrating the Vive hardware with DIY electronics should be entirely possible.

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Commanding Kerbals With A Physical Interface

Kerbal Space Program will have you hurling little green men into the wastes of outer space, landing expended boosters back on the launchpad, and using resources on the fourth planet from the Sun to bring a crew back home. Kerbal is the greatest space simulator ever created, teaches orbital mechanics better than the Air Force textbook, but it is missing one thing: switches and blinky LEDs.

[SgtNoodle] felt this severe oversight by the creators of Kerbal could be remedied by building his Kerbal Control Panel, which adds physical buttons, switches, and a real 6-axis joystick for roleplaying as an Apollo astronaut.

The star of this build is the custom six-axis joystick, used for translation control when docking, maneuvering, or simply puttering around in space. Four axis joysticks are easy, but to move forward and backward, [SgtNoodle] replaced the shaft of a normal arcade joystick with a carriage bolt, added a washer on one end, and used two limit switches to give this MDF cockpit Z+ and Z- control.

The rest of the build is equally well detailed, with a CNC’d front panel, toggle switches and missile switch covers, with everything connected to an Arduino Mega. This Arduino interfaces the switches to the game with the kRPC mod, which creates a script-driven interface to the game. So, toggling the landing gear switch, for instance, triggers a script which interfaces with KSP to lower your landing gear prior to a nice, safe landing. Or, more likely, a terrifying crash.

Star Track: A Lesson in Positional Astronomy With Lasers

[gocivici] threatened us with a tutorial on positional astronomy when we started reading his tutorial on a Arduino Powered Star Pointer and he delivered. We’d pick him to help us take the One Ring to Mordor; we’d never get lost and his threat-delivery-rate makes him less likely to pull a Boromir.

As we mentioned he starts off with a really succinct and well written tutorial on celestial coordinates that antiquity would have killed to have. If we were writing a bit of code to do our own positional astronomy system, this is the tab we’d have open. Incidentally, that’s exactly what he encourages those who have followed the tutorial to do.

The star pointer itself is a high powered green laser pointer (battery powered), 3D printed parts, and an amalgam of fourteen dollars of Chinese tech cruft. The project uses two Arduino clones to process serial commands and manage two 28byj-48 stepper motors. The 2nd Arduino clone was purely to supplement the digital pins of the first; we paused a bit at that, but then we realized that import arduinos have gotten so cheap they probably are more affordable than an I2C breakout board or stepper driver these days. The body was designed with a mixture of Tinkercad and something we’d not heard of, OpenJsCAD.

Once it’s all assembled and tested the only thing left to do is go outside with your contraption. After making sure that you’ve followed all the local regulations for not pointing lasers at airplanes, point the laser at the north star. After that you can plug in any star coordinate and the laser will swing towards it and track its location in the sky. Pretty cool.

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3D Printer Enclosure Is Pleasant On The Eyes And Ears

There’s a lot going on in the 3D printing world. Huge printing beds, unique materials like concrete, and more accessible, inexpensive printers for us regular folk. The only thing that’s often overlooked with these smaller printers is the ruckus that they can make. The sounds of all those motors can get tiresome after a while, which was likely the inspiration for [Fabien]’s home 3D printer workstation. (Google Translate from French)
After acquiring a new printer, [Fabien] needed a place to put it and created his own piece of furniture for it. The stand is made out of spruce and is lined with insulation. He uses a combination of cork, foam, and recycled rubber tile to help with heat, sound, and vibration respectively. Don’t worry, though, he did install a ventilation system for the fumes! After the printer housing is squared away, he place a webcam inside so that the user can monitor the print without disturbing it. Everything, including the current print, is managed with a computer on the top of the cabinet.
Having a good workspace is just as important as having a quality tool, and [Fabien] has certainly accomplished that for his new 3D printer. There have been a lot of good workspace builds over the years, too, including electronics labs in a portable box and this masterpiece workbench. If you’ve ever experienced the frustration of working in an area that wasn’t designed for the task at hand, you’ll easily be able to appreciate any of these custom solutions.

Copenhagen Suborbitals Launches Impressive Amateur Liquid Fueled Rocket

Copenhagen Suborbitals just launched their latest amateur liquid fuel rocket. Why? Because they want to strap someone to a bigger amateur liquid fuel rocket and launch them into space.

We’ve covered them before, but it’s been a while. While they make a big deal of being amateurs, they are the least amateurish amateurs we’ve come across. We’ll forgive a lot as long as they keep making great videos about their projects. Or posting great pictures of the internals of their rockets.

The Nexø I rocket they recently launched claims to be the first guided, amateur, liquid-fueled rocket. There is a nice post on the guidance system. It was launched from a custom built barge off the shore of Denmark, which allows them to escape quite a few legal hurdles around the launch. The rocket flew beautifully. That is, it went only away from the ground; no other directions. Also, it didn’t explode, which is a lot to expect from even the biggest players in the field.

Copenhagen Suborbitals continues to do amazing work. Hopefully their next rocket will be even more impressive… for amateurs, that is.

Modest Motor Has Revolutionary Applications

Satellites make many of our everyday activities possible, and the technology continues to improve by leaps and bounds. A prototype, recently completed by [Arda Tüysüz]’s team at ETH Zürich’s Power Electronics Systems Lab in collaboration with its Celeroton spinoff, aims to improve satellite attitude positioning with a high speed, magnetically levitated motor.

Beginning as a doctoral thesis work led by [Tüysüz], the motor builds on existing technologies, but has been arranged into a new application — with great effect. Currently, the maneuvering motors on board satellites are operated at a low rpm to reduce wear, must be sealed in a low-nitrogen environment to prevent rusting of the components, and the microvibrations induced by the ball-bearings in the motors reduces the positioning accuracy. With one felling swoop, this new prototype motor overcomes all of those problems.

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Fail Of The Week (in 1996): The 7 Billion Dollar Overflow

The year was 1996, the European Space agency was poised for commercial supremacy in space. Their new Ariane 5 Rocket could launch two three-ton satellites into space. It had more power than anything that had come before.

The rocket rose up towards the heavens on a pillar of flame, carrying four very expensive and very uninsured satellites. Thirty-seven seconds later it self destructed. Seven billion dollars of RUD rained down on the local beaches near the Guiana Space Centre in Southern South America. A video of the failed launch is after the break.

The cause of all this was a single improper type cast in a bit of code that wasn’t even supposed to run during the actual launch. Talk about a fail.

There were two bits of code. One that measured the sideways velocity, and one that used it in the guidance system. The measurement side used a 64 bit variable, but the guidance side used a 16 bit variable. The code was borrowed from an earlier, slower rocket whose velocity would never grow large enough to exceed that 16 bits. The Ariane 5, however, could be described with a Daft Punk song, and quickly overflowed this value.

The code that caused the overflow was actually a bit of pre-launch software that aligned the rocket. It was supposed to be turned off before the rocket firing, but since the rocket launch got delayed so often, the engineers made it timeout 40 seconds into the launch so they didn’t have to keep restarting it.

The ESA never placed blame on a single contractor. The programmers had made assumptions. The engineers had made reasonable shortcuts to make their job easier. It had all made it through inspections, approvals, and finally the launch event.

They certainly learned from the event; the Ariane 5 rocket has flown 82 out of 86 missions successfully since then. It has at least five more launches contracted before it is retired in 2023 for the Ariane 6 rocket being developed now. This event also changed the way critical software and redundant systems were tested, bringing the dangers of code failure to the attention of the public for the first time.

If you want to read more, there is a great discussion on Reddit which tipped us off to this fail, a quite thorough Wikipedia article, and the original article that ran in the New York Times is mirrored here.

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